Final answer:
The term used when a consumer pays a flat dollar amount of all expenditures is a co-payment or co-pay, typical in health insurance where it represents shared costs between the insurer and the consumer.
Step-by-step explanation:
The term used when a consumer pays a portion, which is a flat dollar amount, of all expenditures is known as a co-payment or co-pay. This concept is commonly associated with health insurance where a consumer is required to pay a fixed charge for specific services or medication, apart from any deductible or co-insurance they might already have. For example, an individual might have a co-pay of $20 for every doctor's visit or $250 for each visit to the emergency room. This flat fee is paid by the consumer at the time of service and represents a shared cost between the insurance provider and the consumer, which can impact the overall health care expenditure and consumer behaviour.